projects/linux·blob v6.12 · refs

300 lines · 7.2 KiB

1#!/bin/sh
2# SPDX-License-Identifier: GPL-2.0
3#
4# link vmlinux
5#
6# vmlinux is linked from the objects in vmlinux.a and $(KBUILD_VMLINUX_LIBS).
7# vmlinux.a contains objects that are linked unconditionally.
8# $(KBUILD_VMLINUX_LIBS) are archives which are linked conditionally
9# (not within --whole-archive), and do not require symbol indexes added.
10#
11# vmlinux
12# ^
13# |
14# +--< vmlinux.a
15# |
16# +--< $(KBUILD_VMLINUX_LIBS)
17# | +--< lib/lib.a + more
18# |
19# +-< ${kallsymso} (see description in KALLSYMS section)
20#
21# vmlinux version (uname -v) cannot be updated during normal
22# descending-into-subdirs phase since we do not yet know if we need to
23# update vmlinux.
24# Therefore this step is delayed until just before final link of vmlinux.
25#
26# System.map is generated to document addresses of all kernel symbols
27
28# Error out on error
29set -e
30
31LD="$1"
32KBUILD_LDFLAGS="$2"
33LDFLAGS_vmlinux="$3"
34
35is_enabled() {
36 grep -q "^$1=y" include/config/auto.conf
37}
38
39# Nice output in kbuild format
40# Will be supressed by "make -s"
41info()
42{
43 printf " %-7s %s\n" "${1}" "${2}"
44}
45
46# Link of vmlinux
47# ${1} - output file
48vmlinux_link()
49{
50 local output=${1}
51 local objs
52 local libs
53 local ld
54 local ldflags
55 local ldlibs
56
57 info LD ${output}
58
59 # skip output file argument
60 shift
61
62 if is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT; then
63 # Use vmlinux.o instead of performing the slow LTO link again.
64 objs=vmlinux.o
65 libs=
66 else
67 objs=vmlinux.a
68 libs="${KBUILD_VMLINUX_LIBS}"
69 fi
70
71 if is_enabled CONFIG_MODULES; then
72 objs="${objs} .vmlinux.export.o"
73 fi
74
75 objs="${objs} init/version-timestamp.o"
76
77 if [ "${SRCARCH}" = "um" ]; then
78 wl=-Wl,
79 ld="${CC}"
80 ldflags="${CFLAGS_vmlinux}"
81 ldlibs="-lutil -lrt -lpthread"
82 else
83 wl=
84 ld="${LD}"
85 ldflags="${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux}"
86 ldlibs=
87 fi
88
89 ldflags="${ldflags} ${wl}--script=${objtree}/${KBUILD_LDS}"
90
91 # The kallsyms linking does not need debug symbols included.
92 if [ -n "${strip_debug}" ] ; then
93 ldflags="${ldflags} ${wl}--strip-debug"
94 fi
95
96 if is_enabled CONFIG_VMLINUX_MAP; then
97 ldflags="${ldflags} ${wl}-Map=${output}.map"
98 fi
99
100 ${ld} ${ldflags} -o ${output} \
101 ${wl}--whole-archive ${objs} ${wl}--no-whole-archive \
102 ${wl}--start-group ${libs} ${wl}--end-group \
103 ${kallsymso} ${btf_vmlinux_bin_o} ${ldlibs}
104}
105
106# generate .BTF typeinfo from DWARF debuginfo
107# ${1} - vmlinux image
108gen_btf()
109{
110 local btf_data=${1}.btf.o
111
112 info BTF "${btf_data}"
113 LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${PAHOLE_FLAGS} ${1}
114
115 # Create ${btf_data} which contains just .BTF section but no symbols. Add
116 # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all
117 # deletes all symbols including __start_BTF and __stop_BTF, which will
118 # be redefined in the linker script. Add 2>/dev/null to suppress GNU
119 # objcopy warnings: "empty loadable segment detected at ..."
120 ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \
121 --strip-all ${1} "${btf_data}" 2>/dev/null
122 # Change e_type to ET_REL so that it can be used to link final vmlinux.
123 # GNU ld 2.35+ and lld do not allow an ET_EXEC input.
124 if is_enabled CONFIG_CPU_BIG_ENDIAN; then
125 et_rel='\0\1'
126 else
127 et_rel='\1\0'
128 fi
129 printf "${et_rel}" | dd of="${btf_data}" conv=notrunc bs=1 seek=16 status=none
130
131 btf_vmlinux_bin_o=${btf_data}
132}
133
134# Create ${2}.o file with all symbols from the ${1} object file
135kallsyms()
136{
137 local kallsymopt;
138
139 if is_enabled CONFIG_KALLSYMS_ALL; then
140 kallsymopt="${kallsymopt} --all-symbols"
141 fi
142
143 if is_enabled CONFIG_KALLSYMS_ABSOLUTE_PERCPU; then
144 kallsymopt="${kallsymopt} --absolute-percpu"
145 fi
146
147 info KSYMS "${2}.S"
148 scripts/kallsyms ${kallsymopt} "${1}" > "${2}.S"
149
150 info AS "${2}.o"
151 ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \
152 ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} -c -o "${2}.o" "${2}.S"
153
154 kallsymso=${2}.o
155}
156
157# Perform kallsyms for the given temporary vmlinux.
158sysmap_and_kallsyms()
159{
160 mksysmap "${1}" "${1}.syms"
161 kallsyms "${1}.syms" "${1}.kallsyms"
162
163 kallsyms_sysmap=${1}.syms
164}
165
166# Create map file with all symbols from ${1}
167# See mksymap for additional details
168mksysmap()
169{
170 info NM ${2}
171 ${NM} -n "${1}" | sed -f "${srctree}/scripts/mksysmap" > "${2}"
172}
173
174sorttable()
175{
176 ${objtree}/scripts/sorttable ${1}
177}
178
179cleanup()
180{
181 rm -f .btf.*
182 rm -f System.map
183 rm -f vmlinux
184 rm -f vmlinux.map
185}
186
187# Use "make V=1" to debug this script
188case "${KBUILD_VERBOSE}" in
189*1*)
190 set -x
191 ;;
192esac
193
194if [ "$1" = "clean" ]; then
195 cleanup
196 exit 0
197fi
198
199${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init init/version-timestamp.o
200
201btf_vmlinux_bin_o=
202kallsymso=
203strip_debug=
204
205if is_enabled CONFIG_KALLSYMS; then
206 true > .tmp_vmlinux.kallsyms0.syms
207 kallsyms .tmp_vmlinux.kallsyms0.syms .tmp_vmlinux0.kallsyms
208fi
209
210if is_enabled CONFIG_KALLSYMS || is_enabled CONFIG_DEBUG_INFO_BTF; then
211
212 # The kallsyms linking does not need debug symbols, but the BTF does.
213 if ! is_enabled CONFIG_DEBUG_INFO_BTF; then
214 strip_debug=1
215 fi
216
217 vmlinux_link .tmp_vmlinux1
218fi
219
220if is_enabled CONFIG_DEBUG_INFO_BTF; then
221 if ! gen_btf .tmp_vmlinux1; then
222 echo >&2 "Failed to generate BTF for vmlinux"
223 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF"
224 exit 1
225 fi
226fi
227
228if is_enabled CONFIG_KALLSYMS; then
229
230 # kallsyms support
231 # Generate section listing all symbols and add it into vmlinux
232 # It's a four step process:
233 # 0) Generate a dummy __kallsyms with empty symbol list.
234 # 1) Link .tmp_vmlinux.kallsyms1 so it has all symbols and sections,
235 # with a dummy __kallsyms.
236 # Running kallsyms on that gives us .tmp_kallsyms1.o with
237 # the right size
238 # 2) Link .tmp_vmlinux.kallsyms2 so it now has a __kallsyms section of
239 # the right size, but due to the added section, some
240 # addresses have shifted.
241 # From here, we generate a correct .tmp_vmlinux.kallsyms2.o
242 # 3) That link may have expanded the kernel image enough that
243 # more linker branch stubs / trampolines had to be added, which
244 # introduces new names, which further expands kallsyms. Do another
245 # pass if that is the case. In theory it's possible this results
246 # in even more stubs, but unlikely.
247 # KALLSYMS_EXTRA_PASS=1 may also used to debug or work around
248 # other bugs.
249 # 4) The correct ${kallsymso} is linked into the final vmlinux.
250 #
251 # a) Verify that the System.map from vmlinux matches the map from
252 # ${kallsymso}.
253
254 # The kallsyms linking does not need debug symbols included.
255 strip_debug=1
256
257 sysmap_and_kallsyms .tmp_vmlinux1
258 size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso})
259
260 vmlinux_link .tmp_vmlinux2
261 sysmap_and_kallsyms .tmp_vmlinux2
262 size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso})
263
264 if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
265 vmlinux_link .tmp_vmlinux3
266 sysmap_and_kallsyms .tmp_vmlinux3
267 fi
268fi
269
270strip_debug=
271
272vmlinux_link vmlinux
273
274# fill in BTF IDs
275if is_enabled CONFIG_DEBUG_INFO_BTF; then
276 info BTFIDS vmlinux
277 ${RESOLVE_BTFIDS} vmlinux
278fi
279
280mksysmap vmlinux System.map
281
282if is_enabled CONFIG_BUILDTIME_TABLE_SORT; then
283 info SORTTAB vmlinux
284 if ! sorttable vmlinux; then
285 echo >&2 Failed to sort kernel tables
286 exit 1
287 fi
288fi
289
290# step a (see comment above)
291if is_enabled CONFIG_KALLSYMS; then
292 if ! cmp -s System.map "${kallsyms_sysmap}"; then
293 echo >&2 Inconsistent kallsyms data
294 echo >&2 'Try "make KALLSYMS_EXTRA_PASS=1" as a workaround'
295 exit 1
296 fi
297fi
298
299# For fixdep
300echo "vmlinux: $0" > .vmlinux.d